Searching \ for '[EE]: Underwater IR Photoreflector' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: www.piclist.com/techref/io/irs.htm?key=ir
Search entire site for: 'Underwater IR Photoreflector'.

Exact match. Not showing close matches.
PICList Thread
'[EE]: Underwater IR Photoreflector'
2002\08\26@145213 by Donovan Parks

flavicon
face
Hello,

I'm trying to build an underwater tachometer for an AUV (autonomous underwater vehicle) being built at the University of Victoria by a group of engineering students.  What we hope to do is the standard shaft encoder scheme where one determines speed by counter the number of strips that pass by a photoreflector for a given time period.  As such, we are looking for an IR photoreflector that is contained in a waterproof casing (maximum depth we will be going is 30 feet).  Can anyone recommend such a photoreflector or an alternative way to match the speed of two motors?

Regards,
Donovan

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics


2002\08\26@150502 by Peter L. Peres

picon face
>I'm trying to build an underwater tachometer for an AUV (autonomous
>underwater vehicle) being built at the University of Victoria by a group
>of engineering students.  What we hope to do is the standard shaft
>encoder scheme where one determines speed by counter the number of strips
>that pass by a photoreflector for a given time period.  As such, we are
>looking for an IR photoreflector that is contained in a waterproof casing
>(maximum depth we will be going is 30 feet).  Can anyone recommend such a
>photoreflector or an alternative way to match the speed of two motors?

Search for fiber optic coupled industrial optocouplers. Then you can put
them in a dry place and glue the fiber head into a suitable flange or
gland as you need.

Peter

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics


2002\08\27@050650 by Samuel BOUQUET

flavicon
face
>I'm trying to build an underwater tachometer for an AUV (autonomous
>underwater vehicle) being built at the University of Victoria by a group
>of engineering students.  What we hope to do is the standard shaft
>encoder scheme where one determines speed by counter the number of strips
>that pass by a photoreflector for a given time period.  As such, we are
>looking for an IR photoreflector that is contained in a waterproof casing
>(maximum depth we will be going is 30 feet).  Can anyone recommend such a
>photoreflector or an alternative way to match the speed of two motors?

Try a Hall effect sensor, with a magnet on the other side of the gap, like
OHB900 from OPTEK (http://www.optekinc.com) and glue it.
In france, Farnell sold it (http://www.farnell.com)

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.


2002\08\27@131648 by Jim

flavicon
face
I had an idea that pulses caused by the brushes on the commutator could be
conditioned to digital levels and used as an encoder. Connecting a scope
to a small dc motor while running shows a pulse of 20mv whose frequency is
in proportion to the speed. It seems like capacitive coupling and amplifier
to the motor and maybe using a schmitt trigger at the amp out would be a working
alternative to opto sensors.

Hope this helps

James M

At 11:51 AM 8/26/02 -0700, you wrote:
>Hello,
>
>I'm trying to build an underwater tachometer for an AUV (autonomous
underwater vehicle) being built at the University of Victoria by a group of
engineering students.  What we hope to do is the standard shaft encoder
scheme where one determines speed by counter the number of strips that pass
by a photoreflector for a given time period.  As such, we are looking for an
IR photoreflector that is contained in a waterproof casing (maximum depth we
will be going is 30 feet).  Can anyone recommend such a photoreflector or an
alternative way to match the speed of two motors?
{Quote hidden}

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.


2002\08\27@220813 by Roman Black

flavicon
face
Jim wrote:
>
> I had an idea that pulses caused by the brushes on the commutator could be
> conditioned to digital levels and used as an encoder. Connecting a scope
> to a small dc motor while running shows a pulse of 20mv whose frequency is
> in proportion to the speed. It seems like capacitive coupling and amplifier
> to the motor and maybe using a schmitt trigger at the amp out would be a working
> alternative to opto sensors.


Hi Jim, here's one i've been using for years;
http://www.romanblack.com/encoder.htm

It needs some motor load (ie brush current) to
work and its not great for wide speed control.
It is ok for a simple tacho or for relatively
constant loads like fans, spindles etc. :o)
-Roman

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.


2002\08\28@102347 by Jim

flavicon
face
Thanks Roman

James M


{Quote hidden}

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email spam_OUTlistservTakeThisOuTspammitvma.mit.edu with SET PICList DIGEST in the body


More... (looser matching)
- Last day of these posts
- In 2002 , 2003 only
- Today
- New search...